In a conventional measurement system, the input range setting is one of the most important settings. For example, in an analysis system there may be a number of different input voltage range settings for each input channel. The input range setting has a direct impact on the quality of measurement, which is mainly reflected by SNR (Signal-to-Noise Ratio) or dynamic range. Users are often troubled by being unable to set the optimum range because the measured signal either is non-stationary or has an unknown amplitude. For a high channel count system having multiple relevant input ranges, it is even more difficult to get all the input ranges to their suitable value. To deal with this situation, many instruments are designed with an intelligent auto-ranging capability. “Auto-ranging” tries to set the best input range based on a certain measurement before the test actually begins. The auto-ranging can only deal with stationary or repetitive signals, i.e., those signals without many magnitude changes. For non-stationary signals such as electricity transients, auto-ranging usually does not work because each pulse may take a different magnitude. For a signal with long time history and a large range of amplitude change, auto-ranging cannot be applied at all, because during the measurement procedure it is not allowed to change the input range, i.e., the amplifier gain setting.
As described in the publication “New Technology Increases the Dynamic Ranges of Data Acquisition Systems Based on 24-Bit Technology,” in SOUND AND VIBRATION, April 2005, pages 8-11, Andersen et al. state that sound and vibration transducers (e.g., microphones) have outperformed the subsequent analysis systems in linearity and dynamic performance. For such a system, the ratio between the highest and lowest signal level the system can handle is defined as its “dynamic range.” The publication states that if the dynamic range is too low, high signals will typically be clipped and distorted while the low signals will typically be buried in system noise that originates from the transducer element and the electronics conditioning the transducer. As a solution, the publication describes utilizing a specialized analog input designed to provide a very high dynamic range of analog circuit pre-conditioning the transducer signal before forwarding the signal to a pair of specially designed 24-bit analog-to-digital converters (ADCs). Both data streams from the ACDs are forwarded to a digital signal processing environment, where dedicated algorithms in real-time merge the signals.
While prior art approaches operate well for their intended purposes, additional advances are sought.